1. Field of the Invention
The present invention relates to the preparation of N-phenylbenzoquinone-imine by oxidation of N-(4-hydroxyphenyl)aniline.
This invention also relates to the reaction of the N-phenylbenzoquinone-imine thus obtained with an aliphatic or cycloaliphatic amine, to prepare an N-phenyl-N'-cycloalkylparaphenylenediamine and an N-phenyl-N'-cycloalkyl-2,5-cyclohexadiene-1,4-diimine (this latter compound is itself easily reduced to the corresponding N-phenyl-N'-cycloalkylpara-phenylenediamine).
2. Description of the Prior Art
The N-phenyl-N'-alkyl-paraphenylenediamines are currently prepared, in particular, by reduction, then by alkylation of para-nitrodiphenylamine.
Thus, U.S. Pat. No. 4,463,191 describes a process for the reduction/alkylation of para-nitrodiphenylamine, with ketones or aldehydes, in the presence of palladium/anthranilic acid complex fixed onto an unbranched polymer, and in the presence of a sulfonated resin. The catalyst is required to be prepared in several stages.